Potentials and problems of building detailed dust records using peat archives: An example from Store Mosse (the "Great Bog"), SwedenVisa övriga samt affilieringar
2016 (Engelska)Ingår i: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 190, s. 156-174Artikel i tidskrift (Refereegranskat) Published
Abstract [en]
Mineral dust deposition is a process often overlooked in northern mid-latitudes, despite its potential effects on ecosystems. These areas are often peat-rich, providing ample material for the reconstruction of past changes in atmospheric deposition. The highly organic (up to 99% in some cases) matrix of atmospherically fed mires, however, makes studying the actual dust particles (grain size, mineralogy) challenging. Here we explore some of the potentials and problems of using geochemical data from conservative, lithogenic elements (Al, Ga, Rb, Sc, Y, Zr, Th, Ti and REE) to build detailed dust records by using an example from the 8900-yr peat sequence from Store Mosse (the "Great Bog"), which is the largest mire complex in the boreo-nemoral region of southern Sweden. The four dust events recorded at this site were elementally distinct, suggesting different dominant mineral hosts. The oldest and longest event (6385-5300 cal yr BP) sees a clear signal of clay input but with increasing contributions of mica, feldspar and middle-REE- rich phosphate minerals over time. These clays are likely transported from a long-distance source (< 100 km). While dust deposition was reduced during the second event (5300-4370 cal yr BP), this is the most distinct in terms of its source character with [Eu/Eu*] UCC revealing the input of plagioclase feldspar from a local source, possibly active during this stormier period. The third (2380- 2200 cal yr BP) and fourth (1275-1080 cal yr BP) events are much shorter in duration and the presence of clays and heavy minerals is inferred. Elemental mass accumulation rates reflect these changes in mineralogy where the relative importance of the four dust events varies by element. The broad changes in major mineral hosts, grain size, source location and approximated net dust deposition rates observed in the earlier dust events of longer duration agree well with paleoclimatic changes observed in northern Europe. The two most recent dust events are much shorter in duration, which in combination with evidence of their local and regional character, may explain why they have not been seen elsewhere.
Ort, förlag, år, upplaga, sidor
2016. Vol. 190, s. 156-174
Nyckelord [en]
Mineral dust, Peat, Geochemistry, Sweden, Paleoclimate, Holocene
Nationell ämneskategori
Geokemi Geofysik
Identifikatorer
URN: urn:nbn:se:umu:diva-128973DOI: 10.1016/j.gca.2016.06.028ISI: 000388802600010Scopus ID: 2-s2.0-84978785876OAI: oai:DiVA.org:umu-128973DiVA, id: diva2:1060497
2016-12-282016-12-202023-03-24Bibliografiskt granskad